Enable simd for the Crossover plugin

plugins/crossover/Cargo.toml

@@ -8,5 +8,11 @@ license = "GPL-3.0-or-later"
 [lib]
 crate-type = ["cdylib"]
 
+[features]
+default = ["simd"]
+# Make it go fast, vroom. Requires a nightly compiler. Non-SIMD builds are
+# currently unsupported.
+simd = ["nih_plug/simd"]
+
 [dependencies]
 nih_plug = { path = "../../", features = ["assert_process_allocs"] }

plugins/crossover/README.md

@@ -25,9 +25,9 @@ on macOS.
 
 ### Building
 
-After installing [Rust](https://rustup.rs/), you can compile Crossover as
-follows:
+After installing **nightly** [Rust](https://rustup.rs/) toolchain, you can
+compile Crossover as follows:
 
 ```shell
-cargo xtask bundle crossover --release
+cargo +nightly xtask bundle crossover --release
 ```

plugins/crossover/src/lib.rs

@@ -14,6 +14,11 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
+#![cfg_attr(feature = "simd", feature(portable_simd))]
+
+#[cfg(not(feature = "simd"))]
+compile_error!("Compiling without SIMD support is currently not supported");
+
 use nih_plug::prelude::*;
 use std::sync::Arc;